Forest Health: Prescribe Burning

The Daniel Boone National Forest uses prescribed fire and mechanical treatments to reduce the risk of wildland fire, improve wildlife habitat and riparian zones, control noxious weeds and improve watershed and range conditions in eastern Kentucky.

Historically:

The historic suppression of fire has resulted in a lack of periodic, natural fire in our forest. The absence of these low intensity fires has increased the risk of large fire events and has negatively impacted the health of our forests. As part of an effort to use fire as a resource management tool, the Daniel Boone National Forest is reviewing existing resource management and fire management plans to develop an integrated fire planning strategy.

Prescribed fires are used on public lands in order to improve forest health, and reduce large wildfires. Prescribed fire is used only under appropriate conditions and in appropriate sites. The Forest Service has identified areas where prescribed fire can be used as a management tool.

Historic Role of Fire:

• Fire plays an important and critical role in influencing vegetation and the lifecycles of trees and plant communities. Many species are dependent on fire.
• The historic suppression of fire has resulted in a lack of periodic, natural fire in our forest. The absence of periodic, low intensity fires have increased the risk of large fire events and has negatively impacted the health of our forests.
• Due to our successful prevention and suppression efforts, fire patterns were markedly altered during the past century.
• In the absence of fire, massive insect and disease epidemics and various other forest health problems have proliferated.

Need for Prescribed Fire:

• Prescribed fire will help the Forest Service achieve improved forest and rangeland health and will help reduce the threat of large fire events.
• Prescribed fire allows the Forest Service to control the effects of fire, its location and intensity.
• Prescribed fires can be managed or controlled to reduce the intensity and magnitude of bigger wildfires by reducing the accumulation of flammable fuels.
• Wildfires threaten public safety, impair forest and ecosystem health, and degrade air quality.
• Wildfires can pose serious threats to public health and safety, as well as to air quality. Because the fires are uncontrolled, they pose significant threats to the safety of firefighters and general public and destroy property. The intense or extended periods of smoke associated with uncontrolled fires can also cause serious health problems and significantly decrease visibility. Prescribed fires are used to minimize the emissions and adverse impacts of smoke on public health and the environment.

What is "Prescribed Fire"?

Prescribed fire is any fire intentionally ignited to meet specific land management objectives, such as to reduce flammable fuels, restore ecosystem health, recycle nutrients, or prepare an area for new trees or vegetation. Prescribed fire is a management tool that when used under specifically controlled conditions will help land stewards manage forests and rangelands for multiple use.

Land management agencies have done a tremendous job educating the public about the dangers of wildland fire and reducing the number of human caused fires. However, it is important to realize that not all fire is bad. In fact, many of our ecosystems are dependent on fire.
1. Fire historically crept through these areas with low intensity.
2. Every 5 to 15 years, fire regenerated the forest and cleansed the understory of potential hazardous fuels. These historic fires were not the devastating wildfires of recent years.
3. Frequent cool fires acted as a natural agent reducing surface fuels and all but eliminated large, stand replacing, fire events that have become too frequent during the last three decades.

Fire exclusion practices have resulted in forests being plagued with a variety of problems, including overcrowding resulting from encroachment of species normally eliminated by fire; vulnerability of trees to insects and disease; and inadequate reproduction of fire resistant species. In addition, heavy accumulation of fuel -- dead vegetation of forest floors-- can cause catastrophic fires, threaten public safety, impair forests and ecosystem health, and degrade air quality.

The Forest Service has made it a priority to reintroduce fire into fire dependent ecosystems to help promote ecosystem health. Prescribed fire is viewed by the land management agencies as an agent of change that helps "mother nature" return an ecosystem to its historic range.

When to Use "Prescribed Fire"?

Understanding fire is a science. The ability to know when an ecosystem is ready for prescribed fire is science. When a land management agency restores fire to a given area, they first must define the objectives that the prescribed fire would achieve. There are also many elements of nature that must be just right to meet the objectives of prescribed fire, from both dead and live fuel moistures, air temperature, to wind speed and humidity. This is referred to as the "burn window," the preplanned condition targeted for burning. Due to the uncertainty of these natural elements, fire specialists monitor the critical elements of nature.

Prescribed Fire and Air Quality

How fire affects air quality depends on many factors, including weather conditions, such as wind and humidity; the scope and severity of the fire; and the type and quantity of fuels burned. Smoke contains a number of pollutants. Tiny particles created from the smoke is a concern because it can cause serious health problems. Smoke also adversely affects the clarity of our air, which in turn, affects the distance and sharpness of what we see.

Unplanned or unwanted fires can pose serious threats to public health and safety, as well as to air quality. Because these fires are uncontrolled, they can pose significant threats to the safety of firefighters and the general public, as well as destroy property.

On the other hand, planned or managed fires, are used to minimize the emissions and adverse impacts of smoke on public health and the environment. Many techniques are used to manage the impacts from smoke, including scheduling burning during favorable weather conditions and controlling the amount of fuel and acreage burned. In addition, all planned fire activities are already subject to state air quality regulations.

Fuels in your National Forest

Fire has been a natural part of this forest's ecosystem for a very long time. Throughout time wildfires ignited and burned naturally through the forest. Some were caused by lightning and some were intentionally started by Native Americans. These low intensity fires in the past kept the forest floor free from the natural annual build up of tree needles, dead grass, thick brush, and dead trees. As a result, fire has shaped vegetation patterns and wildlife distributions in the National Forests.

The next time you are camping, hiking or driving in your National Forest notice how much limb wood, brush, and dense thickets of small trees cover the forest floor. This build up of fuel feeds wildfires. Today, fires that are not caught when they are small quickly build in size and fire intensity into catastrophic wildfires.

The USDA Forest Service uses prescribe burning as its way to put fire back into the ecosystem. As you read on you'll discover the value of prescribe burning in your National Forests.

Nature's way of recycling

Fallen trees and limbs left to rot on the Forest floor will decay at a very slow rate. In fact, large logs can take more than 100 years to decompose. This process is aided by the numerous species of bacteria, insects, and wildlife that live in the decomposing materials. All this rotting is one way that nature recycles nutrients back into the soil. Pine needles decompose very slowly. It takes more than a year for 10% of the pine needles to decay. As a result, year after year, pine needles continue to build up until they are eliminated by fire.

Faster recycling occurs during a fire. Gasses are released into the atmosphere in the form of smoke. In the burned area, nitrogen and other nutrients remain and are leached back into the soil as rain soaks the ground. This is nature's way of rapidly recycling nutrients. Unfortunately, when there's too much fuel on the ground and it's burned in an intense wildfire these benefits are often missing. Intense fires tend to scorch the ground and kill the trees above.

Which is better, slow or fast recycling?

Slowly decomposing materials release nutrients steadily into the soil. This continuous release helps to maintain growth over a long period of time. Decomposition can last indefinitely as long as dead material on the forest floor continues to accumulate. In other areas of the world, a wildfire may happen once every 600 years. In these areas, only decomposition will supply needed nutrients between wildfires.

Wildfires cause fast nutrient recycling. An abundant supply of nutrients helps new seedlings, brush, and grasses to grow quickly and become established following a wildfire. This is nature's way of quick starting a forest. Most of the nutrients are quickly used up; however, more lasting effects occur when they are leached into the soil. It usually takes a few years for the supply of nutrients to return to normal levels.

The forest needs both slow recycling, from decomposition, and fast recycling from fires.  However, fires ignited at the wrong time can quickly turn into catastrophic events.

Wildfires occurred every seven to 25 years in Kentucky's forests prior to the early 1900s. Around 1915 National Forest management policy viewed wildfires as destructive and began putting them all out as quickly as possible. Today we realize the important role fire plays in maintaining healthy National Forests.

Why not prescribe burn everywhere?

Some places are not easy to prescribe burn. These are locations where it may not be economical, feasible, or practical. Exact fire prescriptions are developed by fire managers before burning is allowed. These fire prescriptions are based on weather, moisture content of the fuels, and how the fire can be lighted (ignition patterns). There may only be 50 days in an entire year when an area meets the prescription.

Laws and regulations also determine when a prescribe fire may be ignited. Air quality regulations play an important role. It's not unusual for forest conditions to be in prescription and a no burn day due to poor air quality. Prescribe burning takes place when laws, regulations, and forest needs are all in balance. Prescribe burns also don't take place when there are safety, health, and aesthetic concerns.

The ecosystem of this forest was developed with fire as one of the main sculptors of vegetation found there. Fire related processes need to continue to perpetuate this ecosystem.

Forests, Forest Fires, and Their Makers: The Story of Cliff Palace Pond

by Paul A. Delcourt, Hazel R. Delcourt, Cecil R. Ison, William E. Sharp, and A. Gwynn Henderson

This publication documents how two sciences, archaeology and paleoecology, came together in a research project that confirmed archaeologists' ideas about the changing land use patterns of the First Americans along the western edge of the Appalachian Mountains.  

Soil core studies from this site on the Daniel Boone National Forest show how American Indians used fire to manage the environment for over 3,000 years. This understanding of ancient practices will help guide forest management for the future.

Insect Threats

Chestnut Borer | Gypsy Moth | Hemlock Woolly Aldegid | Southern Pine Beetle | Sudden Oak Death

Other Forest Health Topics

Four Threats to Forest Health | Forest Health Initiative | Red cockaded woodpecker | Invasive Species

Last Updated: July 27, 2009